Norbornene ring-opened polymer hydrogenated products have been conventionally known to have excellent transparency, heat resistance, low birefringence, formability, and the like, and their use as materials for optical disks and optical lenses has been proposed. Since these polymers have other excellent properties such as low dielecticity and chemical resistance, their utilization is expanding to include fields other than optical goods. The norbornene ring-opened polymers and the hydrogenated products used here are usually atactic amorphous polymers in terms of their structure. However, since further improvement in mechanical hardness, solvent resistance, heat resistance, and other properties is desired when using these polymers for applications other than optical use, stereoregular polymerization of norbornene monomers is proposed as a countermeasure.
For example, Organometalics, Vol. 17, pp. 4183-4195 (1998) describes tacticity of a norbornene ring-opened polymer hydrogenated product obtained by the polymerization using a tantalum complex as a polymerization catalyst. Preprint of the Society of Polymer Science, Japan, Vol. 8, pp. 1629-1630 (2002) describes tacticity of a dicyclopentadiene ring-opened polymer hydrogenated product obtained by the polymerization using a tungsten or molybdenum complex with two coordinated biphenoxy groups as a polymerization catalyst. However, the polymers described in these documents are isotactic polymers with a meso diad percentage of 50% or more.
JP-05-345817-A discloses a polymerization catalyst composition consisting of a tungsten compound and an activator for polymerization of non-conjugated polycyclic cycloolefin monomers such as dicyclopentadiene, cyclopentadiene trimer, and the like, in which the tungsten compound is a tungsten-imide compound represented by the formula W(Nra)Xa4-x (Orb)x.L′y, wherein x is an integer of 0-4, y is 0 or 1, ra and rb are respectively an alkyl, phenyl, phenyl-substituted phenyl, or phenylalkyl and so on, Xa is Cl or Br, and L′ represents a donor ligand. However, the polymerization method described in this document is a bulk polymerization method to produce crosslinked polymers which cannot be hydrogenated. In addition, the polymers obtained are supposed to have no stereoregularity.
JP-11-80325-A discloses a ring-opening metathesis polymerization technology of cycloolefins in the presence of a polymerization catalyst consisting of an organic transition metal complex shown by the following formula and an organometal compound,
wherein rc represents alkyl or aryl, rd and re individually represent an alkoxy, aryloxy, alkylamide, or arylamide, Xb and Xc individually represent a halogen, alkyl, aryl, or alkylsilyl, ya represents a phosphine, ether, or amine, N is nitrogen, M′ is a transition metal selected from group 6 of the periodic table, and n′ is an integer of 0-2.
However, it was difficult to obtain a ring-opened polymer and crystalline ring-opened polymer hydrogenated product having a syndiotactic structure by the ring-opening polymerization of the polycyclic norbornene monomers with three or more rings in the presence of the polymerization catalyst described in this document.